Method of and apparatus for coating incandescent lamp filaments and similar articles



Jan. 22, 1935. NEHMERT 1,988,955

- METHOD OF AND-APPARATUS FOR comma INCANDESCENT LAMP v FILAMENTS ANDSIMILAR ARTICLES Filed Jan. 19,1932

FRIEDRICH E. NEFzJME'R 7';

BY W/ 7 WM Patented Jan. 22, 1935 UNITED STATES PATENT OFFICE FriedrichErnst Nehmert, Eindhoven, Netherlands, assignor to General ElectricCompany, a corporation of New York Application January 19, 1932, SerialNo. 587,596 In the Netherlands February 11, 1931 4 Claims.

My invention relates to methods of and apparatus for coatingincandescent lamp filaments and similar articles. More particularly, myin- (Fig. 2) is mounted directly above said wheel 13. The whole assemblyis rapidly rotated with the result that the surface 15 of the solutionin the vention relates to methods of and apparatus ion, tube 12, insteadof assuming a simple paraboloidal 6 applying the so-called getter tocoiled metal filaments. Getters are materials, usually nonmetallic,which are used in incandescent lamps and similar devices for the purposeof improving the performance of the lamp as by improving the vacuum inthe case of vacuum devices, or by combining with metallic vapors andpreventing injurious discoloring of the bulb. v

It is possible to dip the mounted filament into a getter solution but,as ordinarily performed, this method imparts a coating of said solutionto the support wires and the button at the end of the arbor when saidbutton and the filament are in substantially the same plane. Suchcoating of the button and support wires has a detrimental effect on thelight output and current consumption of the lamp which may be due togases formed by a chemical reaction between the getter material and theglass covered by it. One of the objects of my invention is to provide amethod of and apparatus for applying getter by which only the filamentand a comparatively small portion of the support wiresadjacent theretoare coated. According to my invention, this is accomplished by impartinga desired shape to the surface of the getter solution which is obtainedby making the vessel for the getter bath rotatable. According to aprinciple of hydro-mechanics, the surface of a liquid in a vessel whichis rotated with a uniform velocity will assume the shape of aparaboloid. This shape would be satisfactory in the case of someincandescent lamps. However, directing elements are preferably providedin the getter vessel for the purpose of imparting a more desirable shapeto the surface of the solution. Further features and advantages of myinvention will appear from the following description of species thereof.

In the drawing Fig. 1 is an elevation in sec- -tion of a. devicecomprising my invention; Fig. 2 is a top view of a directing element;and Figs. 3 and 4 are top and side views respectively of anotherdirecting element included therein.

Referring to Fig. 1, my invention comprises a vessel 10 mounted on ashaft 11. A directing element 12 comprising a tube which preferably hasan upward sloping inner wall to prevent sticking 01' solid particlesthereto, is located inside of the vessel 10 and is affixed theretothrough another directing element comprising a pick-up wheel 13 (Figs. 3and 4), while another directing wheel 14 shape, takes on the shape shownin Fig. 1 due to the action of wheels 13 and 14. The wheel 14 forces thesolution up through the tube 12 while a stationary blade 16 located inthe vessel 10 but outside the tube 12 prevents a paraboloidal shape ofthe solution in the vessel 10 and by impeding the whirling of thesolution in said container outside of the cylinder 12, assists the wheel13 in forcing said solution up through said tube 12. rection of which isindicated by the arrows in Fig. 1. An electric lamp mount is loweredinto this device as shown in Fig. 1, and a horse-shoe shaped filament1'7 and small portions of leadingin wires 18 and support wires 19comprised in said mount are immersed in' the solution while a button 20of said mount remains clear thereof.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. The method of coating filaments which consists in rotating a vesselcontaining a body of getter solution about its axis to cause saidsolution to have a concave upper surface and then dipping a mountcomprising a filament arranged around a central axial support so thatsaid filament is immersed in said solution and said support remainsclear thereof.

. 2. The method of coating filaments which consists in agitating a.solution to cause it to have a curved upper surface and then dipping amounted filament therein so that only the filament and portions ofsupport wires adjacent thereto will be coated.

3. An apparatus for coating filaments compris ing a vessel, a fluid insaid vessel, a tube vertically disposed in said vessel, the lower end ofsaid tube extending into said fluid, means for rotating said tube, and avertically extending stationary blade disposed outside of and adjacentto said tube and having an end portion extending laterally under thelower edge of said tube.

4. An apparatus for coating filaments comprising a vessel, a fluid insaid vessel, a tube vertically disposedin said vessel, the lower end ofsaid tube extending into said fluid, upwardly directing blades mountedin the lower end of said tube, means for rotating said tube, and avertically extending stationary b ade disposed outside of and adjacentto said tube and having an end portion extending.

laterally under the lower edge of said tube.

' FRIEDRICH ERNST NEHMERT.

Thus a circulation is effected, the di-

